SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9592cf931a85420759e5af032c45d7ab223739c63c3054dcb0cd7815793fa508' 
  AND token = 'yf3ZkorPpsFSG/+BfVnglZvnYssk8WKSD0iJFv4TRYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}